Three Dimensional Application Of Reaction Displacement Method

Under the double carbon background,urban renewal,environmental improvement and ecological construction are the general trend of urban development and a major national strategy.The municipal comprehensive pipe gallery is an effective way to reduce aerial spider webs,improve the environment,eliminate zipper roads and alleviate traffic congestion.At the same time,it is convenient for maintenance,overhaul,monitoring and operation and maintenance.However,the safety and stability of the underground comprehensive pipe gallery needs to be studied,especially the length of the pipe gallery is far greater than the width and height.The deformation and displacement under the conditions of earthquake and uneven foundation settlement directly affect the safe operation of the pipe gallery,which is a major civil problem related to the operation of the city.Through a large number of investigation and literature review,it is found that there are few literatures on the seismic research of underground pipe gallery,especially the literature report on the influence of the length direction of comprehensive pipe gallery under earthquake has not been found.Therefore,aiming at the analysis of the dangerous time and the influence along the length direction of the underground structure under the action of seismic force,this paper uses the response displacement method to establish 3D and 2D numerical analysis models,studies the relative displacement,shear force and acceleration of the underground structure under the action of seismic force,and finds out the most unfavorable state.The main research contents are as follows:(1)The characteristics of one-dimensional free field of soil layer around K0+066～K0+255 pipe gallery of N6 Road Comprehensive Pipe Gallery Project in xiong’an new area under the action of seismic wave with peak acceleration of 0.31 g are studied,the dangerous time of underground structure under seismic force is found,and the physical parameters such as relative displacement,shear force and acceleration at that time are recorded;(2)The original physical model of the reaction displacement method is extended to 3D,the finite element method is used to solve the foundation spring coefficient,the foundation spring in the length direction of the structure is added on the basis of the original physical model,the response of the value of the foundation spring coefficient to the internal force of the structure is studied,the calculation methods of each spring coefficient are compared to find out the correlation and similarities and differences,and the various parameters of the contact surface between the pipe gallery and the soil layer are found out The most reasonable foundation spring coefficient in the X direction and Y direction of the point;(3)The horizontal displacement and stress of 3D pipe gallery model are studied,and the horizontal displacement difference between the top,bottom plate and side wall of 3D model with SOLID65 element as the main body and 2D model with beam element as the main body is compared.The reasons for the difference are analyzed according to the characteristics of main element,setting mode of foundation spring and structural reinforcement diagram.Through the above research,the following conclusions are as follows:(1)It is found that the relative displacement of the soil layer around the K0+066～K0+255 pipe gallery reaches the maximum at 2.85 s under the action of 0.31 g seismic wave;(2)The value of foundation spring coefficient has an important influence on the axial force and shear force of the structure.However,the spring coefficient calculated by Li Yingmin method is smaller,and the finite element method is used to ensure the safety of the structure;(3)The horizontal displacement of the pipe gallery will increase with the increase of the length,but will not increase infinitely.The horizontal displacement in the middle of the pipe gallery will reach stability;(4)Compared with 2D model,3D response displacement method can not only reflect the influence of structural reinforcement mode,but also reflect the response of length characteristics of pipe gallery structure under seismic force.The research conclusion of this paper proves that the experimental results obtained by applying the reaction displacement method in three-dimensional are relatively reliable,have certain practical guiding significance,and can be used as a supplement to the original reaction displacement method.